用python操作和管理ArangoDB

目录:

安装需要用到的python包:

pip install pyarango

一、连接数据库:

>>> from pyArango.connection import *
>>> conn = Connection(username="root", password="root_passwd")

 当该代码执行时,它会初始化 conn 变量上的服务器连接。默认情况下,pyArango会尝试建立与http://127.0.0.1:8529的连接。

二、创建数据库/集合/文档

创建和打开数据库

方法:

createDatabase()

该方法可以在服务器上打开或创建数据库,当要连接的数据库不存在时,pyArango会在服务器上创建它。当它存在时,pyArango会尝试打开数据库。

>>> db = conn.createDatabase(name="school")

也可以使用其名称作为服务器连接上的键来打开现有数据库:

>>> db = conn["school"] >>> db ArangoDB database: school

创建集合

方法:

createCollection()

>>> studentsCollection = db.createCollection(name="Students") >>> db["Students"] ArangoDB Collection name: Students, id: 202, type: document, status loaded

创建文档

方法:

createDocument()

>>> doc1 = studentsCollection.createDocument() >>> doc1["name"] = "John Smith"
>>> doc1 ArangoDoc None: {name: John Smith} >>> doc2 = studentsCollection.createDocument() >>> doc2["firstname"] = "Emily"
>>> doc2["lastname"] = "Bronte"
>>> doc2 ArangoDoc None: {firstname: Emily, lastname: Bronte} 

因为尚未将其保存到ArangoDB,所以该文档显示其 _id 为“None”。这意味着该变量存在于您的Python代码中,但不存在于数据库中。 ArangoDB 通过将集合名称与 __key 值进行配对来构造 _id 值。

保存文档:

>>> doc1._key = "johnsmith"
>>> doc1.save() >>> doc1 ArangoDoc Students/johnsmith: {name: John Smith}

循环输入数据:

>>> students = [(Oscar, Wilde, 3.5), (Thomas, Hobbes, 3.2), ... (Mark, Twain, 3.0), (Kate, Chopin, 3.8), (Fyodor, Dostoevsky, 3.1), ... (Jane, Austen,3.4), (Mary, Wollstonecraft, 3.7), (Percy, Shelley, 3.5), ... (William, Faulkner, 3.8), (Charlotte, Bronte, 3.0)] >>> for (first, last, gpa) in students: ... doc = studentsCollection.createDocument() ... doc[name] = "%s %s" % (first, last) ... doc[gpa] = gpa ... doc[year] = 2017 ... doc._key = ‘‘.join([first, last]).lower() ... doc.save()

三、检索筛选

查看某一个特定学生的GPA:

>>> def report_gpa(document): ... print("Student: %s" % document[name]) ... print("GPA: %s" % document[gpa]) >>> kate = studentsCollection[katechopin] >>> report_gpa(kate) Student: Kate Chopin GPA: 3.8

筛选平均成绩在3.5以上的学生:

方法:

fetchAll()

>>> def top_scores(col, gpa): ... print("Top Soring Students:") ... for student in col.fetchAll(): ... if student[gpa] >= gpa: ... print("- %s" % student[name]) >>> top_scores(studentsCollection, 3.5) Top Scoring Students: - Mary Wollstonecraft - Kate Chopin - Percy Shelly - William Faulkner - Oscar Wilde

四、更新

可以定义一个特定的函数来处理更新:

>>> def update_gpa(key, new_gpa): ... doc = studentsCollection[key] ... doc[gpa] = new_gpa ... doc.save()

五、删除

方法:

delete()

>>> tom = studentsCollection["thomashobbes"] >>> tom.delete() >>> studentsCollection["thomashobbes"] KeyError: ( Unable to find document with _key: thomashobbes, { code: 404, errorNum: 1202, errorMessage: document Students/thomashobbes not found, error: True })

六、调用AQL的方法

除了上面显示的Python方法之外,ArangoDB还提供了一种查询语言(称为AQL),用于检索和修改数据库上的文档。在pyArango中,您可以使用 AQLQuery() 方法执行这些查询。

检索所有文档的_key:

>>> aql = "FOR x IN Students RETURN x._key"
>>> queryResult = db.AQLQuery(aql, rawResults=True, batchSize=100) >>> for key in queryResult: ... print(key) marywollstonecraft katechopin percyshelley fyodordostoevsky marktwain ...

 

 

 

参考资料:

https://www.arangodb.com/tutorials/cn-tutorial-python/